This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-200017, filed Jun. 29, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a disc access apparatus and method for gaining access to, for example, a CD-ROM (Compact Disc ROM) having compressed music data files, etc., recorded therein and a CD-R (Compact Disc Recordable) having recorded music data files, etc., created by a computer.
2. Description of the Related Art
In recent years, various music data file compression techniques have been developed alongside the rapid advances in digital audio. As such compression techniques, there are MP3 (MPEG-1, Audio layer-III), AAC (Advanced Audio Coding), WMA (Windows Media Audio) and so on. Further, CD-ROMs with recorded music data files compressed by the use of such compression techniques are commercially available and CD-Rs are available in which music data files compressed by the use of a personal computer are recorded.
In the case of the audio CD, the number of programs recordable in the CD is restricted to 99 at max. In the case where a music data file (hereinafter referred to as an MP3 file) is recorded as a file compressed by, for example, MP3 in the CD-ROM and CD-R, the number of recordable programs, that is, the number of MP files, is practically unlimited. It is, therefore, possible to record a greater number of programs in the CD-ROM and CD-R as long as the recording capacity allows it.
FIG. 8 diagrammatically shows the logic format of a CD-ROM. This logic format controls a file with the use of a directory or folder concept. Here, it is to be noted that the directory and folder are used to mean the same thing. The address of a plurality of folders 1, 2, . . . , n, with an MP3 file stored therein, together with the address of the root directory, are recorded in a path table. The address of each folder and address of the root directory are managed with the use of the path table. Although, in FIG. 8, the folders are shown as constituting a one-layer structure, if any subfolders are provided in the respective folder, the address of the subfolder is managed by the path table.
In the case where, in the logic format thus arranged, a required MP3 file is to be searched, it is necessary to sequentially trace the root directory, folder and MP file by referring to the path table. It, therefore, takes longer to make such a search. For this reason, in the case where, in particular, any program largely distant from a currently played-back program is reproduced without sequentially reproducing continuous programs, it takes longer to reach that program for reproduction.
It is considered that, when a CD-ROM or CD-R is set in a reproducing device for reproduction, a table is created in an initializing stage which can gain direct access to a memory of the reproducing apparatus to get an MP3 file.
FIG. 9 shows one form of a table FAT created in a memory. The table FAT comprises file names of the MP3 file and addresses representing, for example, head addresses of the MP3 file. In the table FAT, the file name and address are stored in a way to correspond to a given program. Such a table is created in the initializing stage with the CD-ROM or CD-R set in the reproduction device. When a desired program number is designated, direct access can be made to the MP3 file corresponding to the program number by referring to the table. Therefore, it is possible to search a desired program at high speed. Further, the file name (program name) can be displayed by reading out a file name corresponding to the searched program.
In general, however, the address of the file is allowed to have a length of a few bytes and the file name is allowed to have a length of, for example, about 128 bytes. Further, the number of files recorded in the CD-ROM or CD-R is substantially unlimited. For this reason, there is a problem that, when many files are involved, the size of the table becomes greater and it is necessary to provide a memory section of a greater capacity. Therefore, a need is created for a disc access apparatus and method which, even if a greater number of files are involved, can achieve a high-speed search and require no memory section of a greater capacity.
According to an aspect of the present invention, there is provided a disc access apparatus comprising a storage section configured to store data from a reproducing section configured to reproduce data stored in a disc, the storage section including a first table for storing a folder address representing a position of each folder read out from the disc and a second table for setting, to a first value, a bit corresponding to an initial file in the read-out respective folder and setting a bit corresponding to another file to a second value.
According to an aspect of the invention, there is provided a disc access method comprising the steps of storing, in a first table, a folder address representing a position of each folder read out from a disc and setting, to a first value, a bit corresponding to an initial file in the read-out respective folder in a second table and setting a bit corresponding to another file in the second table to a second value.